Telephony.



E. R. CORWIN.

TELEPHONY.-

APPLICATION HLED APR-5,1913.

Patented May 30, 1916] 3 SHEETS-SHEET I.

INVENTOR ELMER R. coRwne- ATTORNE 4 E. R. CORWIN.

TELEPHONY.

APPLICATION FILED APR. 5, 1913.

Patented May 30,1916.

3 SHEETSSHEET 2.

L i L WITNESSES INVENTOR ELMERR.GORWIN BY W ATTORN E. R. CORWIN.

TELEPHONY.

APPLICATION FILED APR. s. 1913.

- 1,185,372. Patented May 30, 1916.

3 SHEETS-SHEET 3.

FEES INVE NT 0R {iZ/JI 3 ELI/IE3. R. CORWIN I BY ATTQBNEY a. UNITED STATESPATENT OEFICE.

ELMER R. CORWIN, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, T0

FRANK B. COOK COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS,

rntnrrronv.

Specification of Ii'etters Patent. I

Application filed April 5', 1913. Serial No. 759,022.

To all whom it may concern Be it known that I, ELMER R. CORWIN, citizen of the United States, residing at Chicago, in the county of Cook and State I of Illinois, have invented a certain new and useful Improvement in Telephony, of which the followingis a full, clear, concise, and exact description, reference beinghad to the accompanying drawings, forming a My invention relates to telephone exchange systems and has for one of its objects the provision of equipment whereby an idle link connector of each group of link connectors is preselected for use and in realizing this feature of my invention master switches are employed one for each group and common to the link connectors thereof and the link connectors are provided with signals, the master switches coming into association with unemployed link connectors and effecting the operation of the signals ing current switch with'the link connectors of a group, this master switch being desirably the same master switch that preselects a link connector for use. i By this feature of my invention manual ringing keys or switches do not need to-be made individual to the link connectors.

My invention. has for another of its objects the provision of means whereby the operators telephone equipment is brought into association with the link connectors that are placed in selectable condition or otherwise predetermined for use, so that the operators are at once in communication with calling subscribers when they select such link connectors.

In the preferred embodiment of theinvention means are employed which are controlled by calling subscribers to bring the r qperators telephone equipment into connec-. the bell and condenser n bridge of the zasso-f ,above tion with the link connectors which the call ing subscribers place in condition for selec tion by ensuing calling subscribers.

By means of'the system of my invention all line and supervisory signals may be" dispensed with and the operators may each be equipped with but a single key which is brought into relation with each of such oper ators link connectors as said link connectors for taking part in establishing ringing and testing circuits.

In practising my invention I employ master switch which is in interchangeable relation with the link connectors for various purposes forming objects of my invention and, in addition to the purposes specifically outlined, the i maste'rf switch also enables the junction of the sec! tions of link connectors with which it'fbe comes associated, the completion of test cir' cuits, the prevention of the application of ringing current to busy lines in cooperation with test relays that are individual to: the

link connectors, and the transmission of busy test manlfestations to calling lines.

While I have somewhat specifically def scribed the nature of variousaspects ofmyf invention as it has been embodied it'isap parent to those skilled in the art that the invention is of abroad nature and is not to be limited to the specific embodiments of its various features herein disclosedg There are also features of the invention which do not depend upon the employment of master switches-as willbe apparent when; the invention is fullyunderstood. My invention has other features and, in

' Patented May 30, 1 916. 1

its preferred embodiment, will' befully de scribed by reference to the accompanying drawings in which Figures 1, 2 and 3, taken in numerical order with the lines at the ends of the sheets in alinement, together illustrate a telephone exchange system equipped in accordance with the invention.

I have illustrated two stations and each having the usual telephonic equipment] comprising a telephone switch h ook"1,a"telephone receiver 2, a; telephone'traiismitter 3, a call bell 4; and a condenser 5," the switch havinga normal contact adapted-to include ciate telephone line sides and an alternate contact for including the receiver and transmitter inbridge of the associate telephone line sides Assuming that the subscriber at station 120 is a calling subscriber and that such subscriber desires communication with stationarmature switch. of relay 7 and its normal contact, the lower winding of relay 7, which is in differential relation with the upper winding of this relay and in equal magnetizing effect therewith, the relay 8, the relay 9, to ground. The relay 9 is common to a gHalp of telephone lines, say one hundred, and the armature switch of this relay, when attracted upon the establishment of such a circuit as that which has been traced, itself establishes a circuit traceable from ground, the armature switch of the relay 9, the contact engaged by this armature switch, the wiper 10, the waiting contact 11, the left hand armature switch of a relay 12 and its contact, a relay 13, to the grounded battery 6. The wiper 10 and a companion wiper 14 form elements of a calling subscriber operated setting up or selector switch indi vidual to each relay 9, each group of one hundred lines having such a setting up or selector switch, there being as many such selector switches as there are groups of telephone lines, though the invention is not to r be limited to the employment of selector "switches which are common to telephone lines. 7

The-wipers 10 and 14 are carried by a ratchet wheel 15 which is turned by means of a motor magnet 16 to bring the wipers 10 and 14 into engagement with waiting contacts 11 and 17 belonging to an idle master switch and individual to a pair of relays 12 and 13, the wipers 10 and 14 normally resting in engagement with such a pair of waiting contacts 11 and 17 so that there is always a master. switch having such waiting contacts 11, 17 in association with the group of one hundred lines and in readiness to be employed by a calling line of such group in extending such calling line into connection with a called line. There are two sets of waiting contacts 11 and 17 each pertaining to a master switch. and there is a pair of such master switches individual to a group of line joining link connectors. The upper master switch being now associated with the calling'line and. its relay 13 being energized, the left hand armature switch of this relav establishes a circuit treaceable from the grounded battery 6 through the interrupter 18, the left hand-armature switch of relay 13 and its engaged contact, the intermediate armature switch of relay 12 andits engaged contact, the wiper 19 of the employed master switch, the waiting contact 20 engaged by the wiper 19, the motor magnet 21 with which the employed master switch happens to be in connection and belonging to an idle link connector of the group of link connectors to which such master switch is common, to the lowermost and grounded armature switch of relay 22 by way of its left hand normal contact. The interrupter 18 thereupon causes the motor magnet 21 intermittently to be operated to rotate the ratchet wheel 23 to bring the wipers 24, 25 and 26 into engagement with waiting contacts individual to the calling line, the operation of the motor magnet 21 ceasing when the wiper 26 engages the calling line'waiting contact that is locally grounded by the armature switch of relay 8 of the calling line, the contact of this armature switch being connected with and individual to such waiting contact thus engaged by the wiper 26.

\Vhen the armature of relay 8 is attracted a circuit is established traceable from this armature switch, which is grounded, the contact then engaged by this armature switch, the waiting contact engaged by the YVlPBI'zQG, the waiting contact 27 of the employed master switch, the wiper 28 resting in: engagement with this waiting contact, the various wipers of the master. switch normally resting in engagement with the waiting contacts of such idle link connector, the left hand winding of relay 12, the right hand armature switch of relay 13 and its engaged contact to the grounded battery 6. The circuit for the motor magnet 21 is now opened consequent upon the energization of the relay 12 at the intermediate armature switch of such relay so that the motor magnet 21 ceases its operation and allows its wipers 24, 25 and 26 to remain in engagement with the waiting contacts engaged thereby and which are individual to the callingline. When the relay 12 is ener gized it establishes a holding circuit for itself that is traceable from its grounded right hand armature switch, the intermediate contact engaged by said armature switch, the right hand winding of relay 12, the wiper 29 of the master switch, the waiting contact 30 engaged by this wiper, the relay 31, the uppermost armature switch of relay 22 and its normal follow-up contact, the wiper 24 and the calling line waiting contact engaged thereby, the upper winding of relay 7, to the grounded battery 6. The windings of the differential relay 7 are now unbalanced in magnetizing effect so that this relay is effectively energized, .the armature switch of this relay being attractedto with the waiting contact of the calling line engaged by the wiper 252 The lower armature switch of the relay 7 in leaving its normal contact breaks the circuit for the lower moved and maintainedfrom the callingline.

waiting contacts engaged by the wiper 26 520 that no other set of wipers 24, 25, 26 will i become connected with the calling line, it being understood that the various wipers 24,- and 26 of eachline seeking switch pass over the waiting contacts of the g roup of one hundred lines, similarly positioned waiting contacts being in multiple connec 25 tion, W hen the relay 12 is-energized' its right hand armature switch establishes a I circuit traceable from this switch, which is grounded, through the lowermost contact of this switch, the waiting contact 17 indi- 30 vidual to this switch contact, the wiper 14,

j the motor magnet 16, to the grounded batm'tery 6 whereby. the wipers 10 and 14 are -.moved into connection with thewaiting contacts 'll, 17 of'an iidle master switchwhich s5 iswlving in association with another link. I

A guarding cirenit is established for the fupper master switch traceable from the right hand grounded armature switch of relay 12,1

the uppermost contact of this switch, the

fan wiper 32 of the upper master switch,wthe I {waiting contact 33 engaged thereby,- the multiple of this waiting contact in the lower master switch (similarly positioned three uppermost waiting contacts of. the

nection) the waiting contact 34 of the lower master switch, the wiper 35 engaging this lower waitingv contact 34, the

150 battery 6 whereby the motor magnet 36, is given one impulse to'move the wipers 28, '29,-etc., carried by its disk 37 out of engagement with its-waitin contacts that are in multiple with the tvvalting contacts engaged by .the wipers of {the upper master switch intoengagement wlth another set of waiting contacts pertaining to another link such, for

example, as the set of waiting contacts pertaining to the lower link and illustrated near the bottom of Fig. 1. Such a stepping move- 1 ment of the wipers of the unemployed mas- I 4 ter switch o'ccurs'ifits wipers happen to be resting upon waiting contacts that are in multiple. with the waiting contacts'engaged by the wipers of the "employed master master switches being in multiple con-' motor magnet 36, directly to the groundedswitch. When the relay 31 is energized its right hand armature switch closes a circuitv which is traceable from the grounded battery 6, through-the interrupter 18, the motor,

magnet 38, the right hand armature switch of relayv 31 and its contact, to the grounded: lowermostiarmature,switch of relay 22 and its right normal contact whereby the motor magnet 38 isintermittently operated to turn the ratchet wheel 39 step by step to bring the wipers 40 and 41 into engagement with waiting contacts 42, 43 pertaining to an idle link"- connector of a succeeding group. The operai tion of the motor magnet 38 continues until its circuit. is opened at the right hand normalicontactof the lower armature switch of so T relay 22, a; result which occurs wheriathefl wipers 40, 41 engage the waiting contacts 42 and 43 of a succeeding'link connector and I this adjusting of-the circuit of the motor magnet 38 at the right hand normalcontact of the lower armature switch of relay 22]. occurs as a result of a circuit that may be traced from ground, the left hand armature switch of relay 31 and its contact, the lower winding of relay "22, similarly w'oundrwithf: respect to its upper winding, the wiper 41, the waiting contact 43 of .the succeeding idle link, the lowermost armature switch of relay 44, and its normal contact, the waiting con-o tact 45, the wiper 46 of an operator selector switch, the right hand armature switch of a relay 47 and its follow-up contact, the relay 47 being individual to an operators, :position and being deenergizcd when the operator is idle, the right hand windingof the relay 47, to the grounded battery 6,. whereupon the relay 47 is energized and the,

operator having the same is protectedv against re-selection while in selected cond-i tion as will appear.

When the relay 22 is energized its armature switches are attracted and the circuit for the motor magnet 38 is opened at the right hand normal contact of the lowermost armature switch of thisrelay whereby the wipers 40 and 41 are arrested in positions to whichthey have been brought where they are in connection with a succeeding link c0n-" for relay 47 which is traceable from the grounded battery 6 the left hand winding of IlBCtOL- A lockingcircuit is now established relay 47, the left hand armature switch of I this relay and its'then engaged contact,

wiper 48 ofthe operator selector. switch,

the waiting contact 49 engaged by this wiper, the uppermost armature switch of.

relay 44 and its normal follow-up contact, the waiting contact 42, the wiper 40, the

uppermost armature switch of relay 22 and its alternate contact, the wiper 24, thc'waiting contact engaged thereby, both sides of the calling line, the lowermost armature switch of relay 7, the alternate contact of this armature switch, the wiper 25 and the waiting contact engaged thereby, the intermediate armaturc switch of relay 22, the left hand alternate contact of this armature switch, the upper winding of relay 22, to

ground. Another locking circuit is also established for relay 22 which is traceable from the grounded battery 6, the upper winding of relay 7 of the calling line, both sides of the calling line, thence by the connections previously traced to the grounded terminal of the upper winding of relay The previously employed master switch having the wipers 28, 19. etc, is now of no further service in establishing the'connection between stations 120 and 190-and its wipers therefore should be stepped off the waiting contacts pertaining to the link connector connected with the calling line, a result which is accomplished by the establishment of a circuit traceable from the grounded battery (3 the motor magnet 36 of the previously employed and upper master switch, the wiper of the upper master switch, the waiting contact 51 engaged by this wiper 50, to the lower grounded armature switch of the relay and its left hand alternate contact whereby the motor magnet 36 of the previously employed master switch is operated to bring its wipers out of engagement with the first link connector that has become connected with the calling line, this movement of these wipers bringing them into connection with the waiting contacts of an idle link connector.

Owing to the connection established at the lower attracted gounded armature switch of relay Q2 pertaining to a link which has become extended into connection with the second link, no master switch can remain in v ing contacts indiyidual to some idle link connector inthe second set that succeedthe first set and it is such idle link connector in the second set that is automati -ally selected by thezgm'otor magnet 38 since such selection depends upon the presence of the magnet 47 that is associated with the idlelink conne'ctorthrough the operator selector switch. The wipers 46 and 48 of the operator selector switch constitute terminals of the operators head telephone and her telephone outfit 52 so that the opera'tors telephone set is in-- cluded in circuit with the calling line simultaneously with the connection of the selected calling subscriber the calling subscriber announces the number of the desired line and come connected with the calling line and which is to be used by the operator in extending the calling line into connection with the called line. The receiver of the operators equipment 53 constitutes a responsive device which is subject to operation of calling subscribers due to the telephonic current which. the calling subscribers impress upon their lines in announcing the designations of the desired lines, but I do not wish to limit myself to the employment of such receivers as calling subscriber operated responsive devices. Thus the selection of the link connector is made for the operator by the calling subscriber and the operator does not arbitrarily select an idle one of her complete group of link connectors. In prior systems the operator was guided in her selection by the physical condition of the various positions of the parts of the link connectors in making her selections. In the present system she is-guided only by the signals 53 and the associate link connectors may have their parts in various adjustments according to the nature of the system. Thus, for example, if the system admitted it, and the system herein shown does, the plug 54 of an idle link connector could remain with- .jack and if a signal were present in association with the plug located within the jack such a signal would mean to the operator that the plug must be taken down. In the present invention a signal displayed in association with a plug located within a jack indicates to the operator that the plug must be withdrawn from its jack and placed in the jack of a called line. If the jack holding the plug belongs to the line wanted the op erator merely allows the plug to remain in suchjack. It is understood that the link connectors having the plugs are, in the embodiment of the invention illustrated, divided into groups, each group having an operators telephone or responsive device equipment 52.which is common to the links 'otits group; The circuit that establishes the signal for the lamp 53 pertaining to a selected link connector is-one which is preterably not established by the calling subf; manifestatiomsuch manifestation being renal.

'scriber but is desirably established by the operator when she selects the idle cord or link that is next to be selected by a calling subscriber, the signal individual to this idle andselectable link glowing so that the operator is informed in advance that the next connection which she is'to put up is to be by means of a link connector having this sig- The circuit for the signal thus estab- 'lished by the operator in connection with a link connector that is next to be selected is traceable from the grounded terminal of the i signal device or lamp 53, through the signal device 53, the waiting contact '56, the wiper -57, to the' grounded battery 6.

It will be understood that the wipers 40 and 41 engage waiting contacts that are individual to different operators positions so i that busy operators will be passed by in the effort to select an idle operator. If the connecting plug 54' is not already within the jack of the desired line it is removed from the position it occupies, either in another jack or upon the plug board and is inserted "completely within a jack of the desired line, no preliminary. testingmotion being necessary. "The operator next partially depresses the plunger of a combined testing and ringing key 58 to bring the smaller of the two spreading portions of the plunger of the left hand spring alone has its-circuit environmentaltered, the'movement then given "to the righthand spring not being sufficient to enable it to engage its contact. The left hand spring is provided with a normal follow-upcontact and, when the key is parv itially depressed, this spring contemporai this connection ofthe left hand spring of neously being in connection with its normal and alternate contacts. As a consequence, of

the key 58' atesting path is established "traceablefrom the grounded battery 6, the

winding offa relay 59, the right hand armature switch of this relay and its normal "follow-up contact, the Waiting contact 60,-

the wiper 61, the left hand spring of the key 58 in its testing position and the two contacts of this spring, the wiper 62, the waiting contact 63, the normalcontact of the right hand arr nature switch of relay 55, the bottom armature switch of relay 74 and its normal follow-up contact, the heel of the inserted plug54, the thimble of the jack '66 of the desired line in which the plug 54 is inserted, thence to the waiting contacts of the desired line provided for engagement with'the wiper-s25.

If the desired line is busy thetest circuitis completed from a wiper 26, the intermediate armature switch of the-relay 22, the left hand alternate con.-

tact of 'this armature switch,the upper winding of the relay 22, to ground. The operator preferably does not receive the busy 'ceived by the calling subscriber as a consequence of the circuit established which may be traced from the grounded battery'6, the testing circuitinterrupter 67, the fivethousand ohm non-inductive resistance 68, both alternate contacts of the right hand armature switch of relay 59 and this armature switch (the relay 59 having had a local circuit established therethrough traceable from the grounded battery 6, 'the winding of relay 59, its right hand armature switch, the upper alternate contact of this armature switch, the waiting contact 42 thence by obvious connections over both sides of the calling telephone line, the wiper 25, the intermediate armature switch of relay 22, the left hand alternate contact engaged by this intermediate armature switch, the upper winding of relay 22, to ground), thence by the portion of the testing path previously traced. to "the grounded terminal of the upper winding of relay-22.

The device 67 will thus cause the vibration of the receiver at the calling station there to furnish the busy test manifestation, and

the calling subscriber may elect to wait until the desired subscriber is free or may restore his telephone to its switch hook in which latter event the relays 7 and 22 are deenergized to restore the equipment to normal. After the operator has afforded opportunity the receiver of the calling subscriber, in the event of-the desired line being busy, such operator will complete the depression of the ringing key 58 to break the test circuit at the normal contact of the left hand spring for a busy test manifestation tooccur 1n of this key and to bring both springs into engagement with the ringing key contacts whereby a circuit is established traceable from' the grounded battery 6, the upper" winding of relay 44, the waiting'contact 69, the wiper 70, the right. hand spring of key 58, the contact engaged thereby, the wiper 48 and the waiting contact engaged thereby, the'upper armature switch of relay 44 and the normal folloW-upcontact of this armature switch, the waiting contact 42, thence by obvious connections over thecalling subscriberls l1ne to the intermedlate armature contac't'of this armature, the upper winding of relay 22, to ground. A locking circuit is now establishedfo'r the relay 44 traceable from the groundedbattery 6, the upper winding of the relay 44, the alternate contact of the upper armature switch of this relay, said'armature switch, thence by the- 'previously traced path to the grounded terminal'of the upperwinding of: relay 22.

Ringing "current isnow applied to the called line by means presently to be 'described, it being stated in passing that the operatorreleases'her key-5s justlafter' she fullyfldepresses it is at'thesame time switch' of relay 22, the left hand alternate -subscriber selection being closed disconnected from the link connector selected by the calling subscriber, it not being necessary for the operator to supervise the ringing operation or any other operation, this result being consequent upon theestablishment of a circuit traceable from the grounded battery 6, the motor magnet 71, the wiper 72, the waiting contact 73, to the intermediate grounded armature switch of relay 44 and the left hand contact of this armature switch. The motor magnet 71 thereul'aon'operates to step the wipers (32, etc.,.which it-vcarries into engagement with the waiting contacts of an unemployed link connector, which unemployedlink connector is thereby placed in condition for selection by a calling subscriber to the exclusion of other unemployed link connectors, the previously displayed lamp 53 having its circuit tact of this armature switch, the inte1.'me-' diate armature switch of relay 5%) and its contact, the intermediate armature switch of a relay 7% and its normal contact, the relay 55, to the grounded battery (3. A ring ing circuit isthereupon established from the grounded ringing generator 75, the lower winding of relay 7.4, the right hand armature switch of relay 55 and its alternate contact, the lowermost armature switch' of relay 74 and its normal follow-up contact, the sleeve of the plug in the desired line, both sides of the desired line by way of the call bell at the station thereof, the tip of the plug 54, the uppermost armature switch of relay 74 and its normal contact, the left hand armature switch of relay 55, to ground. \Vhen the ringing current is passing to the called subscriber a circuit is established for the called subscribers relay 7 'to attract its armature switch and which circuit is traceable from the grounded battery 6, the upper winding of the relay 7 of the called subscriber, the tip of the plug 54 in connection with the called subscribers line, thence by previously traced connections to the grounded let'thand armature switch of relay 55. The signal bells at the subscribers stations are of such high resist- 1 ance that when current from the generator ergize the relay 7-4 whereby the ringing relay 55 is dei nergized owing to the breakage of its circuit at the intermediate armature switch of relay 7%, the relay 55 being maintained inactive owing to the establishment of a locking circuit for the relay 7i traceable from the grounded battery 6, the upper winding of relay 7- the intermediate armature switch of this'relay and its alternate contact, the intermediate armature switch of relay 59 and its contact, the right hand alternate contact of the intermediate tact of this armature switch, the left handarmature switch of relay 59, and the con tact engaging the same, to the grounded lower winding of the relay 4A. The'called subscribers transmitter is furnished with battery current by way .of this" path just traced and the calling subscribers transmitter is furnished with battery current by the path which includes the upper winding of his'relay 7 and the upper winding of the relay22.

When the subscribers are through conversation they restore their receivers to their switch hooks whereby their relays 7 are dci nergized to restore the equipment to normal, the operator taking no part in severing connection between subscribers,

there consequently being no need for supervisory signals. Each operator need be provided with but a single key58 which-is common to the link connectors employed by the operator, this key being related to each link connector as it 'is placed in selectable condition.

While I have herein shown and particularl y described the preferred embodiment of my invention I do not wish to be limited to the precise details of construction and circuit arrangement illustrated as changes may readily be made without departing from the spirit of my invention.

Having thus described my invention I claim as new and desire to secure by Letters Patent the following 1, A telephone exchange system including telephone lines extending to an exchange; groups of link connectors for uniting lines in conversation; a master switch for each group of link connectors and common to the link connectors of such group; means whereby each master switch is normally associated with an idle link connector of its group;

vfor selecting unselected master switches and v the idle link connectors associated therewith; and means governed by calling 'sub-., scribers for establishing connection between selected link connectors and calling lines.

2. A telephone exchange system including telephone-lines extending to an exchange;

in conversation; a master switch for each group of'link connectors and common to ,the link connectors ofsuch group; means whereby each master switch is normally associated with an idle link connector of its group;

selector switches operable. by calling lines for selecting unselected master switches and the idle linkconnectors associated there 7 with; and means governed by calling subscribers for establishing connection between L selected link connectors andcalling lines, "sai'd'linkconnectors being adapted to their line joining function independently of the selector switches. v

3. A telephone exchange system including telephone lines extending to an exchange; groups of link connectors for uniting lines in conversation; a master switch for each group of lmk connectors and common to the link connectors ofsuch group; means whereby each master switch is normally associated with an idle link connector of its, group;

' selector switches operable by calling lines for selecting unselected master switches and the idle link connectors associated;v there-: with; and means governed by calling sub- .s'cribersfor establishing connection' between I (selected link connectors and calling lines 1 and operating to join calling lineswith link connectors independently of the'i selector switches, said linkfconnectors having operator, controlled means for effecting theirconnectionwith further calling line extensions.

4; A telephone exchange system including telephone lines extending to an exchange;

groups of link connectors for unitinglines,

in conversation; a master switch" for each 7 fgroup of link connectors and common to the linkconnectors of such group; means whereby each master switch is normally associated with an idle link connector of its group; selector switches operable bycalling lines for selecting unselected master switches and the idle link connectors associated therewith; and means governed by-calling subscribers for establishing connection between selected link connectors-and calling lines and operating to joinjc'a-lling lines with link connectors independently I of the selector switches, said link connectors having operator controlled means for effecting their connection with further calling line extenj r sions.

5. A telephone exchangesystem including the selector switches.

telephone lines extending to an exchange; selector switches operable by calling, lines groups of link connectors for uniting lines v by each master switch is normally associated 7 with an idle link connector of its group; se

lector switches operable by calling lines for selecting. unselected master switches and the groups of link connectors for unltmg llnes idle link connectors associated therewith; and means governed by calling subscribers for establishing connection between selected link connectors and calling lines, said link connectors having operator controlled means for effecting their connection with further calling line extensions.

6; A telephone exchange'system including telephone lines extending to an exchange;

groups of link connectors for uniting lines in conversation; master switches for each group of link connectors and common to'the link connectors of such group; means whereby each master'switch is normally associated with an idle link connector of its group;

selector switches operable by calling lines .90 for selecting unselected'master switches and the idle link connectors associated there with; and means governed by calling subscribers for establishing connection between selected link connectors and calling lines and operating to join calling lines with lmk connectors independently of the selector switches.

7 A telephone exchange system including for selectingunselected master switches and the idlellink connectors associated therewith; andmeans governed by calling subscribers for moving terminals of selected link connectors into connection with calling lines. v 8.-.A telephone exchange system including telephone lines. extending to an ex change; groups of link connectors for unit-. ing lines inconversation; master switclr for each group of link connectors and common .to the link connectors of such group;

means'whereby each master switch is normally associated with an idle link connector of its-group; selector switches operable iii calling lines for selecting unselected master switches and the idle link connectors associated therewith; and 'means governed: by calling subscribers for movlng termlnals of selected link connectors into connection with calling lines'and operating to joincalling lines with link connectors independently of mally associated with an idle link connector;

of its group; selector switches operable by calling lines for selecting unselected master switches and the idle link connectors associated therewith; and means governed by the selector switche for preventing the master switches pertaining to each group of link connectors from being associated with the same employed link connector and for then associating unemployed master switches with other idle link connectors.

10. A telephone exchange system includ ing telephone lines extending to an exchange; groups of link connectors for unit ing lines in conversation; master switches for each group of link connectors and common to the link connectors of such group; means whereby each master switchis normally associated with an idle link connector of its group; selector switches, each common to a plurality of lines, and operable by callinglines for selecting unselected master switches and the idle link connectors associated therewith; and means governed by the selector switches for preventing the master switches pertaining to each group of link connectors from being associated with the same employed link connector and for then associating unemployed master switches with other idle link connectors.

11. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute .lling line extensions and joining them with calling lines; and meanshaving facility for being set into operation by operators at the exchange for placing link connectors in condition for selection by ensuing calling sub;

scribers and in whose operation equipment of calling lines and link connectors connected therewith take part.

12. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that areto constitute callingline extensions and joining them with calling lines; means having facil ty for being set into operation by operators at the exchange, for

placing link connectors in condition for se lectioi'iiby ensuing calling subscribers; and means for operating the latter means includgi'n'g operator controlled mechanism and.

equipment of calling lines and link connectors joined therewith.

13. Av telephone exchange system including telephone lines extending to an ex change; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means having facility for being set into operation. by operators at the exchange, for placing link connectors in condition for selection by ensuing calling subscribers; and means for operating the latter means including operator controlled mechanism and equipment of calling lines and link connectors joined therewith, each operator having operator controlled mechanism interchange ably associated with her link connectors.

14. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines;

ineans for placing link connectors in condition for selection by ensuing calling subscribers; means for operating the i latter means including operator controlled mechanism and equipment of calling lines and link connectors joined therewith, each operator having operator controlled mechanism interchangeably associated with her liiik connectors; and means jointly controlled by the operator controlled mechanism and the equipment of calling lines and link eonnec tors connected therewith for bringing the operator controlled mechanism into connection with the link connectors to be selected by ensuing calling subscribers.

15. A telephone exchange system including telephone lines extending to an exchange; link connectors t'or uniting lines'in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means for placing link connectors in condition for selection. by ensuing calling subscribers; means for operating the latter means including operator controlled incchanism and equipment of link connectors connected with calling lines, each operator having operator controlled mechanism interchangeably associated with her link connectors; and means in whose operat on equipment of link connectors connected with call ing lines and operator controlled mecha nism take part for bringing the operator controlled mechanism into connection with link connectors to. be selected by ensuing calling subscribers. l

1.6. A telephone exchange ystein including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; and means having facility for being set into operation by operators at the exchange, for placing link connectors in condition for selection by ensuing calling subscribers and in whose operation link connectors joined with calling lines take part. I

17 A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means having facility for being set into operation by operators at the exchange, for placing link connectors in condition for selection by ensuing calling subscribers and in whose operationequipment of calling lines and link connectors connected therewith take part; and signal. devices individual to the link connectors and operated by the equipment pertaining to their link connectors when placed in selectable condition.

18. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means having facility forbeing set into operation by operators at the ex change, for placing link connectors in condition for selection by ensuing calling subscribers; means for operating the latter means including operator controlled mechanism and equipment of calling lines and link connectors joined therewith; and signal devices individual to the link connectors and operated by the equipment pertaining to their link connectorswhen placed in selectable condition.

19. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means having facility for being set into operation by operators at the exchange, for placing link connectors in condition for selection by ensuing calling subscribers;

' means for operatingthe latter means includ ing operator controlled mechanism and equipment of calling lines and link connectors joined therewith, each operator having operator controlled mechanism interchangeably associated with her link connectors; and signal devices individual to the link connectors and operated by the equipment pertaining to their link connectors when placed incselectable condition, before such link connectors are employed by calling lines.

20. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joiningthem with calling lines; means for placing link connectors in condition for selection by ensuing calling subscribers; means for operating the latter means including operator controlled mechanism and equipment of calling lines and link connectors joined therewith, each operator having operator controlled mecha nism interchangeably associated with her link connectors; means jointly controlled by the operator controlled mechanism and the equipment of calling lines and link connectors connected therewith for bringing the operator controlled mechanism into connection with the link connectors to be selected by ensuing calling subscribers; and signal dev ices individual to the link connectors and operated by the equipment pertaining to their link connectors when placedin select-- I able condition.

21. A telephone exchange system includ ing telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute callingline extensions and joining them with calling lines; means for placing link connectors in condition for selection by ensuing calling subscribers; means for operating the latter means including operator controlled mechanism interchangeably associated with her link connectors; means in whose operation equipment of link connectors connected with calling lines and operator controlled mechanism take part for bringing the operator controlled mechanism into connection with link connectors to be selected by ensuing calling subscribers; and signal devices individual to the link connectors and operated by the equipment pertaining to their link connectors when placed in selectable condition.

22. A telephone exchange system includng telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled int switching mechanism for selecting link connectors that are to constitute calling line extensions and oin ng them with call1ngl1nes;

link connectors when placed in selectable condition.

23. A telephone exchange system includ ing telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means having facility for being set into opration by operators at the exchange for placing lin'k connectors in. condition for selection by ensuing calling subscribers and in whose operation equipment of calling lines and link connectors connected there with take part; and an op-cratofis telephone for each group of link connectors and interchangeably associated with link connectors of its group.

.24. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connet-tors that are to constitute calling line extensions and joining them with calling lines; means having facility for being set into operation by operators at the exchange for placing link connectors in condition for seelection by ensuing calling subscri ers; means for operating the latter means including opcator controlled mechanism and equipment calling lines and link connectors joined therewith; and an operators telephone for each group link connectors and interchangeably associated with the link connectors of its group.

A telephone exchange system includi g telephone lines extending to an exchange; link comiectors for unitii'ig lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions a d joining them with calling lines; means having facility for being set into operation'by operators at the exchange, for placing link connectors in condition for so lection by ensuing calling subscribers j means for operating the latter means including operator controlled mechanism an: equipment of calling lines and link connectors joined therewith, each operator ha ing operator controlled mechanism interchangeably associated with her link connectors; and an operators telephone for each group of link connectors and interchangeably associated with the linkconnectors of its group.

meaaw 26. A telephone exchange system incluo ing telephone lines extending to an exchange; link connectm's tor uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them "ith calling lines; means for placing link connectors in condition for selection by ensuing calling subscribers; meansior operating the latter means including operator controlled i'nechanism and equipment oi? calling lines and link connectors joined therewith each operator having opcrahiir controlled mechanism interclmngcably associated with her link connectors; means jointly controlled by the operator controlled mechanism and the equipment of calling lines and link connectors connected there.- with for bringing the operator controlled mechanism into connection with, tl e link connec ors to be selected by ensuing calling subscribers; and an operators telephone each group (it link connectors and inter changeably associated "ith'the link connectors 01'. its group.

A telephone exchange system including telepln'inc lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link coin nectors that are to constitute calling line erc tensions and joining them with calling lines; means for placing link connectors in condition :i'lor selection by ensuing calling sub scribcrs; means for operating the latter means in ,;:ludi;ug operator controlled mechanism and equipment of link connectors con-- nectcd with calling lines, each operator having operator controlled mechanism inten changeably associated with her link coin nectors; means in whose operation-equip ment of link connectors connected with ealling lines and operator controlled mechanism take part for bringing the operator controlled incchanism into connection with link connectors to be selected by ensuing calling subscribers; and an operatofis telephone for each group oi link connectors and intcrchangeablv associated with the link corp necto-v roup.

28. A telephone exchange system inclurl 111g tele t hone lines extending 5,0 an exchange; link connectors tor uniting lines in conversation: calling subscriber controlled switching DIGCllllllSlTi for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means having facility for being set into operation by operators at the exchange. for

placing link connectors in. condition for selection by ensuing calling subscribers and in Whose operation link connectors joined with calling lines take part; and an operators telephone for each group of link connectors and interchangeably associated with the link connectors of its group. r

29. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means having facility for being set into operation by operators at the exchange, for placing link connectors in con dition for selection by ensuing calling subscribers and in whose operation equipment of calling lines and link connectors connected therewith take part; and an operators responsive device for each group of 'link'connectors and interchangeably associated with the link connectors of its group.

30. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means having facility for being set into operation by operators at the exchange,

for placing link connectors in condition for selection by ensuing calling subscribers; means for. operating the latter means including operator controlled mechanism and equipment. of calling lines and link connectors joined therewith; and an operators responsive device for each group of link connectors and interchangeably associated with the link connectors of its group.

31. A telephone excl'iange system including telephone lines extending. to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to-constitute calling line extensions and joining them with calling lines; means having facility for being set into'operation by operators at the exchange, for placing link connectors in condition for selection by ensuing calling subscribers; means for operating the latter means including operator controlled mechanism and equipment of calling lines and link connectors joined therewith, each operator having operator controlled mechanism interchangeably associated with her link connectors; and an operators respons lve device for each group of link connectors and interchangeably associated with the link connectors of its group.

32. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled fswitching mechanism for selecting link connectprs that are to constitute calling line extensions and joining them with callingllines;

means for placing link connectors in condition for selection by ensuing calling subscribers; means for operating the latter means including operator controlled mechanism and equipment of calling lines and link connectors joined therewith, each operator having operator controlled mechanism interchangeably associated with her link connectors; means jointly controlled by the operator controlled mechanism and. the equipment of calling lines and link connectors connected therewith for bringing the operator controlled mechanism. into connection with the link connectors to be selected by ensuing ralling subscribers; and an operators responsive device for each group of link connectors and interchangeably associated with the link connectors of its group A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means for placing link connectors in condition for selection by ensuing calling ing operator controlled mechanism inter- -changeably associated with her link connectors; means in whose operation equipment of link connectors connected with calling lines and operator controlled mechanism take part for bringing the operator controlled mechanism into connection with link connectors to be selected. by ensuing calling subscribers; and an operators responsive device for each group of link connectors and interchangeably associated with the link connectors of its group.

34.. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them -with calling lines; means having facility for being set into operation by operators at theexchange,

for placing link connectors in condition for ing' telephone" lines extending to an ex-- change; link connectors-for uniting lines in conversation and divided into groups; calling subscriber controlled switching I mechalection nism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means for placing link connectors in condition. for seby ensuing calling subscribers; means for ope 'ating the latter means ineluding operator controlled mechanism and equipment ojl. calling lines and link connectors joined therewith; and an operators telephone for each group of link connectors of its group and associated with a link connector, placed in condition for selection, by said operator controlled mechanism and equipment of a calling line and link connector joined therewith.

36. A telephone exchange system including telephone lines extending to an ehang link connectors for uniting lines in .-onversation and divided into groups; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means for placing link connectors in condition for se lcction by ensuing calling subscribers; means .i'or operating the latter means including operator controlled mechanism. and equitment of calling lines and link connectors joined therewith, each operator having operator controlled mechanism interchange ably associated with her link connectors; and an operators telephone for each group of link connectors and common. to and interchangeably associated with the link. connectors of its group and associated with a link connector, placed in condition for selection, by said operator controlled mechanism and equipment of a calling line and link connector joined therewith.

3'7. A telephone exchange system including telephone lines extending to an exchange; link connectors tor uniting lines in conversation and divided into groups; calling subs riber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means for jr'lacing link connectors in condition for selection by ensuing calling subscribers:means for operating the latter means including operator controlled mechanism and equipment of calling lines and link connectors joined therewith, each operator having operator controlled mechanism interchangeably associated with her link connectors; means jointly controlled by the operator controlled mechanism. and the equipment of calling lines and link connectors connected therewith to): bringing the operator controlled mechanism into connection with the link connectors to be selected by ensuing calling subscribers; and an operator's telephone for each group of link connectors and common to and interchangeably associated with the link connectors of its group and associated with a link connector, placed in condition for selection, by said operator controlled mechanism and. equipment of a calling line and link connector joined therewith.

38. A telephone exchange system includ ing telephone lines extending toan exchange; link connectors foruniting lines in cmiversation and divided into groups; ealling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means for placing link connectors in condition for selection by ensuing calling subscribers means for operating the latter means including operator controlled mechanism and equipment of link connectors connected with calling lines, each operator having operator controlled mechanism interchangeably associated with her link connectors; means in whose operation equipment of link eonnectors connected with calling lines and operator controlled mechanism take part for bringing the operator controlled mechanism int-o connection with link connectors to be selected by ensuing calling subscribers; and an operatofis telephone for. each group of link connectors and common to and interchange: bly associated with the link connectors of its group and associated with a link connector, placed in condition .tor selection, by equipment of link connectors connected with calling lines and operator controlled mechanism when employed in placing such link connectors in selectable condition.

39. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation and divided into groups; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute callin line extensions and joining them with calling lines; means for placing link connectors in condition for selection by ensuing calling subscribers and in whose operation link connectors joined with calling lines take part; and an operators telephone for each group of link connectm's and common to and interchangeably associated with the link connectors of its group and associated with a link connector,

placed in condition for ter means.

40. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation and divided. into groups; calling SlllflSClil'lOl controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means for placing link connectors in condition for se lection by ensuing calling subscribers; and an operators telephone "for each group of link connectors and common to and intersclection, by the latchangeably associated With the link connectors of its group and associated with a link connector, placed in condition for selection,

by the latter means.

7 d1. A telephone exchangesystem including telephone lines extending to an exchange; link connectors for uniting lines in ing them with calling lines; means for placing link connectors in condition for selection by ensuing calling subscribers; means for operating the latter means including oper-- ato'r controlled mechanism and equipment o't' calling lines and link connectors oined therewith; and an operators responsive de rice for each group of link connectors of its group and associated with a link connector, placed in condition for selection, by said .operator controlled mechanism and equipment of a calling line and link connector joined therewith.

A telephone exchange system includ-' ing telephone lines extending to an exchange; liiik connectors for uniting lines in conversation and divided into groups; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means for placing link connectors in condition for selection by ensuing calling subscribers; means for operating the latter means including operator controlled mechanism and equipment of calling lines and link connectors joined therewith, each operatorhaving operator controlled mechanism interchangeably assoriated with her link connectors; and an operators responsive device for each group of link connectors and common to and interchangeably associated with the link connectors of its group and associated. with a link .-onneetor, placed in condition for selection, by said operator controlled mechanism and cqui 'iment of a calling line and link connector joined therewith.

43. A telephone exchange system including telephone lines extcni ling to an exchange; link connectors for uniting lines in conversation and divided into grouper calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means for placing link connectors in condition for selection by ensuing calling, subscribers; means for operating the latter means including operator controlled mechanism and equipment-oi calling lines and link connectors joined therewith, each operator having operator controlled mechanism interchangeably associated with her link connectors: means jointly controlled by the operator controlled mechanism and the equipment of calling ,lines and link connectors connected therewith for bringing the operator controlled mechanism into connection with the link connectors to be selected by ensuing calling subscribers; and an operators responsive device for each group of link connectors and common to and interchangeably associated with the link connectors of its group and associated with a link connector, placed in condition for selection, by said operator controlled mechanism and equipment of a calling line and link connector joined therewith.

44c. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation and divided into groups; calling subscribercontrolled esiyitching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means for placing link connectors in condition for selection by ensuing calling subscribers; means for operating the latter means including operator controlled mechanism and equipment of link connectors connected with calling lines, each operator having operator controlled mechanism interchangeably associated with her link connectors; means in Whose operation equipment of link connectors connected vwith calling lines and operator controlled mechanism take part for bringing the operator controlled mechanism into connection with link connectorsto be selected by ensuing calling subscribers; and an operators responsive device for each group of link connectors and common to and interchangeably associated with the link connectors of its group and associated with a link connector, placed in condition for selection, by equipmentof link connectors connected with calling lines and operator controlled mechanism when employed in placing'siich link connectors in selectable condition. 45. A telephone exchange system includmg telephone lines extending to an exchange; link connectors for uniting lines in conversation and divided into groups; calling subscriber controlled switching ineclianisin for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means for placing link connectors in condition for selection by ensuing calling subscribers and. in whose operation link connectors joined with calling lines take part; and an operators responsive device for-each group of link connectors and common to and interchangeably associated with the link connectors of itsgroup and associated with a link connector, placed in condition for selection, by the latter means.

46. A telephone exchange system including telephone lines extending to an ex-- conversation and divided into groups; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and joining them with calling lines; means for placing link connectors in condition for selection by ensuing calling subscribers; and an operators responsive device for each group of link connectors and common to and interchangeably associated with the link connectorsof its group and associated with a link connector, placed in condition for selection, by the latter means.

N. A telephone exchange system includ .ing telephone lines extending to an exchange; link connectors for uniting telephone lines and divided into groups; signal devices individual to each link connector; a switching device for each group of linkcoin ncctors and common to the link connectors of its group; selector witches operable by calling lines for selecting unemployed switching devices; and operator controlled means for associating each switching device -'with an idle link connector to predeterminc the link connector to be taken for use, the switching device when thus associated *ith a link connector serving to operate the signal device individual to such link connector. 48. A telephone exchange system including'telephone lines extending to an change; link. coi' nectors for uniting telephone lines and divided intogronps; signal devices individual to each link connector;

a switching device for each group of link connectors and common to the link connectors of its group; selector switches operable by calling lines for selecting unemployed switching devices; and means for as sociating each switching device with an idle link connector to predetermine the link con hector to be taken for use, the switching device when thus associated with a link connector serving to operate the signal device individual to such link connector.

4L9. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting telephone lines and divided into groups; signal devices individual to each link connector; a switching device for each group of link connecto'rs and common to the link connectors of its group; selector switches operable by calling lines for selecting unemployed switching devices; and means into whose control the equipment of a link connector connected with a calling lino enters for associating each switching device with an idle link connector to predetorininc the link connector to be taken for use, the switching dcvice when thus associated with a link connector serving to operate the signal device individual to such link connector.

50. A telephone exchange systmn includ ing telephone lines extcndi change; link connectors for uniting telephone lines and divided into groups; signal devices individual to each link connector; a switching device for each group of link connectors and common to the link connectors of its group; selector switches operable by calling lines for selecting unemployed switching devices; means into whose control the equipment of a link connector connected with a calling line enters for associating each switching device with an idle link connector to predetermine the link connector to be taken for use, the switching de* vice when thus associated with a link connector serving to operate the signal device individual to such link connector; and operators equipment cooperating with said link connector equipment in controlling said means.

51. A. telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation and which are provided with operator controlled means for enabling their connection with called lines; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions; and means having facility for being set into operation by operators at the exchange, in interchangeable v relation with the link connectors for rendering them selectable by calling subscribers.

52. A telephone exchange system including telephone lines extending to an ex change; link connectors for uniting lines in conversation and which are provided with operator controlled means for enabling their connection with called lines; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions; automatically operating means for rendering link connectors selectable and means, governed by open ators at the exchange, for setting the aforesaid means into operation. 53. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting linesin conversation. and which are provided with operator controlled means for enabling their connection with called lines; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions; automatically ope 'ating means in intr-vchange able relation with the link connectors for rendering them. selectable by ca ling subscribers and means, governed b operators at the exchange, for setting the :ntorcsaid means into operation.

54. A telephone exchange system including telephone lines extending to an exrhangc link connectors for uniting lines in conversation andwhich are provided with operator controlled means for enabling their connection with called lines; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions; and means having facility for being set into operation by operators at the exchange, in interchangeable relation with the link connectors for rendering them selectable by calling sub scribers, the link connectors having equipment each operating when pertaining to a selected link connector to take part in the operation of the aforesaid means to render an idle link connector selectable.

55. A telephone exchange system including telephone lines extending to exchange; link connectors for uniting lines in conversation and which are provided with operator controlled means for enabling their connection with called lines; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions; automatically operating means for. rendering the link connectors selectable, the link connectors having equipment each operating when pertaining to a selected link connector to take part in the operation of the aforesaid means to render an idle link connector selectable and means, governed by operators at the exchange, for setting the aforesaid means into operation." I

56. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation and which are provided with operator controlled means for enabling their connection with called lines; calling subscriber controlled switching mechanism for selecting link connectors that are'to constitute calling line extensions; automatically operating means in interchange able relation with the link connectorsfor renderingthem selectable by calling subscribers, the link connectors having equipment each operating when pertaining toa selected link connector to take part in the operation of the aforesaid means to render an idle link connector selectable and, means,

governed by operators at the exchange, for setting the aforesaid means into operation.

57. A, telephone exchange system includ-' ing telephone lines extending to an exchange; link connectors for uniting lines in conversation'and which are provided with operator controlled means for enabling their connection with called lines; calling subscri er controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and join them with calling lines; and means having facility for being set into operation by operators at the exchange, in interchangeable relation with the link connectors for rcndcring them selectable by calling subscribers.

58. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation and which are provided with operator controlled means for enabling their connection with called lines; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and join them with calling lines; automatically operating means for rendering link connectors selectable and means, governed by operators at the exchange, forisetting the'aforesaid means into operation.

59. A telephone exchange system including telephone lines extending to an ex change; link connectors foruniting lines in, conversation and which are provided with operator controlled means for enabling theirconnection with called lines; calling-subscriber controlled switching mechanism for selecting link connectors that are to consti tute calling line extensions and join-themwith calling lines; automatically operating means in interchangeable relation With the link connectors for rendering them selectable by calling subscribers and means, gov; -erned by operators at the exchange, for-set- I ting the aforesaid means. into operation.

60. A. telephone exchange system includ ing telephone lines extending to amilexchange; link connectors for uniting lines in conversation and which are provided with operator controlled means for enabling their connection with called lines; calling sub scriber controlled switching mechanism for selecting link connectors thatare to constitute calling line extensions and join't-he m with calling linesg'means in interchangeable relation with the link connectors fer rendering them selectable by calling subscribers lw the link connectors having equipment each. operating when pertaining to a selected link" connector to take part in the pperation of the ilfOl'lllCl means to render an idle' link connector selectable and. means, governedUO by operators at'the exchange, for setting the aforesaid means into operation.

61. A telephone exchange system including telephone lines extending to an exchange; link connectors for uniting lines in conversation and which are provided with operator controlled means for enabling their .connection with called lines; calling subscriber controlled switching mechanism for selecting link connectors that are to consti- 12o tute calling line extensionsandfjoin them with calling lines; automatically operating means for rendering the link connectors selectable, the link connectors having equipmenteach operating when pertaining to a selected link connectorto take part in the operation of the aforesaid means to render an idle link connector selectable and means,- governed by operators at the exchange, for

setting the aforesaid means into operation.

62. A telephone exchange system includ ing telephone lines extending to an ex-- change; link connectors for uniting lines in conversation and which are provided with operator controlled means for enabling their connection with called lines; calling subscriber controlled switching mechanism for selecting link connectors that are to constitute calling line extensions and join them with calling lines; automatically operating means in interchangeable relation with the link connectors for rendering them selectable by calling subscribers, the link connectors having equipment eachoperating when pertaining to a selected link connector to take part in the operation of the aforesaid means to render an idle link connector selectable and means, governed by operators at the exchange, for setting the aforesaid means into operation.

63. A telephone exchange system including telephone lines; motor devices for extending the circuits of the telephone lines;

a master switch. common to said motor de vices and provided with means for associating it with an idle motor device to render it operable to extend a calling line; a master motor device common to the telephone lines and operating to select unemployed motor devices and associate them with calling lines; means whereby calling lines may cause the operation of the master motor device to cease when the selected motor device is operated to perform its function; and means governed by the selected motor device for restoring the -master motor device to condition in which it may be controlled by .another calling line.

GJA telephone exchange systemincluding telephone lines; motor devices for OX, tending the circuits of the telephone lines; a master switch common to said motor devices and provided with means for associating it with an idle motor device to render it operable to extend acalling line; a master motor device common to the telephone lines and operating to select unemployed motor devices and associate them with calling lines; means whereby calling lines may cause the operation of the master motor device to cease when the selected motor device is operating to perforn'i its function; and means governed by the selected motor device for setting the master motor device into operation to enable it to be subject to the control of another calling line.

65. A telephone exchange system including telephone lines; normally idle motor devices for extending the circuits of the telephone lines; a master switch common to said motor devices and provided with means for associating it with an idle motor device to render it operable to extend a call ug line; a master motor device common to the telephone lines and operating to select andto 7 set into operation unemployed motor devices and associate them with calling lines; means whereby calling lines may cause the operation of the master motor devices to cease when the selected motor device is operating to perform its function; and means governed by the selected motor device for restoring the master motor device to condition phone lines, and operating to select unemployed motor devices and associate them;

with calling lines; means whereby calling lines may cause the operation of the master motor device to cease when the selected motor device is operating to perform its function; and means governed by the selected motor device for setting the master motor device into operation to enable it to be subject to the control of another calling line.

67. A telephone exchange system including telephone lines; a group of motor de vices less in number than the telephone lines for extending the circuits of the teleplmne lines; a master switch common to said motor devices and provided with means for associating it with an idle motor device to render it operable to extend a calling line; a master motor device common to the telephone lines and operatingto select unemloyed motor devices and associate them with calling lines; means whereby calling lines may -ause the operation of the master motor device to cease when the selected motor do *ice is operated to perform its function; and means governed by the selected motor device for restoring the master motor device to condition in which it may be con" trolled by another calling line.

68. A telephone exchange system including telephone lines; a group of motor de vices less in number than the telephone lines for extending the circuits of the telephone lines; a u'laster switch common to said motor devices and providcd with means for associating it with an idle motor device to render it operable to extend a calling line; a master motor device common to the telephone lines and operating to select unemployed motor devices and associate them with calling lines; means whereby calling lines may cause the operation of the master motor device to cease when the selected motor device is operating to perform its functionrand means governed bythe'se- ,lected' motor device for setting the master motor deviceinto operation to enable it to be subject to the control of another calling line.

69.-A telephone exchange system including telephone lines; 'a group of normally idle motor devices less in-number than the telephone lines for extending the "circuits of the telephone lines; a master switch common to said motor devices and provided with means for associating it with an idle motor device to render it operable to extend a calling line; a master motor device v common to the telephone lines and operat-r ing to-select and-to set into operation unemployedmotor devices and associate them with calling lines; means whereby calling lines mayjcause the operation of the master motor device to cease when the selected motor device is operating to perform its function;a'nd means governed by the selected motor device for restoripg the master motor device'to condition in which it may becontrolled by another calling line. a

TOL-A telephone exchange system including telephone lines; a group of normally idle motor devices less in number than the telephone lines for extending the circuits of the telephone lines; a master switch common to said motor devices'and provided withjmeans for associating it with an idle 1 motor device to render it operable to extend a calling line; a master motor device common to the telephone lines and operating to select unemployed motor devices and associate them with calling lines; means whereby calling lines may cause the opention of the master motor device to cease when the selected motor device is operating to perforin'its function; and means governed by the selected motor device for setting the master motor device into operation to enable it to be subject to the control of another calling line.

T1."A telephone exchange system including telephone lines; link connectors for uniting the lines in. conversation; motor devices forextending calling lines into connectionwith the link connectors; a master switch common to said motor devices and provided with means for associating it with an idle motor device to render it operable to extend 'a calling line; a master motor devicecommon to the telephone lines and operating to select unemployed 'motor-de vices and associate them with calling lines;

. means whereby calling lines may cause the operation of the master motor device to cease when the selected motor device is operatedto perform its function; and means governed by the selected motor device for restoring the master motor device to condiother calling line.

72. A telephone .excliange sys em" iii-club ing telephone 1ines';l1n'k connectors for nection with the link connectors; a master switch common to sald IIIOtOI' dGVICQS and provided with'means for associating it with an idle motor device to render it operable to extend a calling line; a master motor device common to the telephone lines and operating to select unemployed motor devices and associate them with calling lines; means whereby calling lines may cause. the operation of the master motor device to cease when the selected motor device is operating to perform its function; and means governed by the selected motor device for setting the master motor device into operation to enable it to be subject to the control of another calling line.

73. A telephone exchange system includ "ing telephone lines; link connectors for uniting the lines in conversation; normally idle motor devices for extending calling lines into connection with the link connectors; a master switch common to said motor devices and provided. with means for associating it with an idle motor device to render it operable to extend a calling line; a master motor device common to the telephone lines and operating to select and to set into operation unemployed motor devices and associate them with call:

ing lines; means whereby calling lines may,

cause the operation of the master motor device to cease when the selected motor device is operating to perform its function; and means governed by the selected motor with calling lines; means whereby calling,

lines may cause the operation of the master motor device to cease when the selected 'mo tor-device is operating to perform its function; and means governed by the selected motor device for'setting the master motor device into operation to enable it to be-subject to the control of another calling line:

75. A telephone-exchange system including telephone lines; link connectors for uniting thelines in conversation; a group of mdtor devices less in number than the "telephone lines iforextending calling lines'n into-connection with the link connectors;'a,

device for restoring the master motor device 

